This invention relates to an improved leak tracer composition or solution for detecting leaks, particularly in the fuel tanks and lines of aircraft, and is particularly concerned with an inproved leak tracer solution of the above type, and which does not adhere to external surfaces contacted by the leak tracer, and which does not stain the painted, and particularly white painted, surfaces of the aircraft.
Newly fabricated fuel tanks and lines for aircraft are generally tested for cracks and leaks before installation in the aircraft, utilizing a leak tracer solution. Such leaks tracer solutions heretofore employed usually consist of water, a detergent, glycerin and a dye, usually a red dye.
However, when employing such conventional leak tracer solutions, the red dye contained in the leak tracing solution tended to permanently stain the white painted surfaces of the aircraft if a spill or leak occurred. Such painted surfaces can be the exterior surfaces of the suel tanks, or other adjacent surfaces of the aircraft such as the wings or other components. Further, a film of the glycerin contained in the formulation adhered to all surfaces contacted by the leak tracer. Also, there were algae-like substances bearing the color of the leak tracer found entrapped in and clogging certain passages of the aircraft's fuel system, and some of the leak tracer solution remained entrapped or "puddled" in depressions and low areas of the fuel tanks and lines. Careful and repeated cleaning was thus necessary until all of the spilled and remaining leak tracer solution was removed, and clogging fuel lines were freed of the leak tracer solution.
Dye penetrant compositions containing nonionic oxyalkylated alcohol surfactants, derived from both primary and secondary aliphatic alcohols, as vehicle, and a dye, are described in my U.S. Pat. Nos. 3,915,885 and 3,915,886. These, however, are non-aqueous solutions which are applied to the external surfaces of test bodies or parts to detect surface flaws or cracks therein by retention of dye penetrant in such cracks and flaws, and by viewing such retained dye entrapments under suitable lighting conditions.
Accordingly, an object of the present invention is the provision of an improved leak tracer composition or solution particularly designed for fuel tanks and lines. A further object of the invention is to provide a leak tracer solution of the above type which does not stain the painted, and particularly white painted, surfaces of aircraft. A still further object of the invention is to provide a novel water-based leak tracer solution which does not contain substances such as glycerin which tend to adhere to the interior surfaces contacted by the leak tracer solution, and which do not promote parasitic growth which clog passages, e.g. in aircraft fuel systems. Another object is to provide a simple, inexpensive, highly penetrating and essentially water-based leak tracer solution of the above type, containing a minimum of readily available components. A further object is to provide procedure for detection of cracks and leaks, particularly in aircraft fuel tanks and lines, employing the above leak tracer solution.